Study Title:

Tocotrienols and Tocopherols Reduce Alzheimer’s

Study Abstract

In this study we investigated the association between plasma levels of eight forms of vitamin E and incidence of Alzheimer's disease (AD) among oldest-old individuals in a population-based setting. A dementia-free sample of 232 subjects aged 80+ years, derived from the Kungsholmen Project, was followed-up to 6 years to detect incident AD. Plasma levels of vitamin E (alpha-, beta-, gamma, and delta-tocopherol; alpha-, beta-, gamma-, and delta-tocotrienol) were measured at baseline. Vitamin E forms-AD association was analyzed with Cox proportional hazard model after adjustment for several potential confounders. Subjects with plasma levels of total tocopherols, total tocotrienols, or total vitamin E in the highest tertile had a reduced risk of developing AD in comparison to persons in the lowest tertile. Multi-adjusted hazard ratios (HRs) and 95% confidence interval (CI) were 0.55 (0.32-0.94) for total tocopherols, 0.46 (0.23-0.92) for total tocotrienols, and 0.55 (0.32-0.94) for total vitamin E. When considering each vitamin E form, the risk of developing AD was reduced only in association with high plasma levels of beta-tocopherol (HR: 0.62, 95% CI 0.39-0.99), whereas alpha-tocopherol, alpha- tocotrienol, and beta-tocotrienol showed only a marginally significant effect in the multiadjusted model [HR (95% CI): alpha-tocopherol: 0.72 (0.48-1.09), alpha-tocotrienol: 0.70 (0.44-1.11), beta-tocotrienol: 0.69 (0.45-1.06)]. In conclusion, high plasma levels of vitamin E are associated with a reduced risk of AD in advanced age. The neuroprotective effect of vitamin E seems to be related to the combination of different forms, rather than to alpha-tocopherol alone, whose efficacy in interventions against AD is currently debated.

From press release:

High levels of several vitamin E components in the blood are associated with a decreased risk for Alzheimer's disease (AD) in advanced age, suggesting that vitamin E may help prevent cognitive deterioration in elderly people. This is the conclusion reached in a Swedish study published in the July 2010 issue of the Journal of Alzheimer's Disease.

"Vitamin E is a family of eight natural components, but most studies related to Alzheimer's disease investigate only one of these components, ±-tocopherol," says Dr. Francesca Mangialasche, who led the study. "We hypothesized that all the vitamin E family members could be important in protecting against AD. If confirmed, this result has implications for both individuals and society, as 70 percent of all dementia cases in the general population occur in people over 75 years of age, and the study suggests a protective effect of vitamin E against AD in individuals aged 80+."

The study was conducted at the Aging Research Center (ARC), Karolinska Institutet, Stockholm, Sweden, in collaboration with the Institute of Gerontology and Geriatrics, University of Perugia, Italy. The study included a sample of 232 participants from the Kungsholmen Project, a population-based longitudinal study on aging and dementia in Stockholm (Kungsholmen parish). All participants were aged 80+ years and were dementia-free at the beginning of the study (baseline). After 6-years of follow-up, 57 AD cases were identified.

The blood levels of all eight natural vitamin E components were measured at the beginning of the study. Subjects with higher blood levels (highest tertile) were compared with subjects who had lower blood levels (lowest tertile) to verify whether these two groups developed dementia at different rates. The study found that subjects with higher blood levels of all the vitamin E family forms had a reduced risk of developing AD, compared to subjects with lower levels. After adjusting for various confounders, the risk was reduced by 45-54%, depending on the vitamin E component.

Dr Mangialasche notes that the protective effect of vitamin E seems to be related to the combination of the different forms. Another recent study indicated that supplements containing high doses of the E vitamin form ±-tocopherol may increase mortality, emphasizing that such dietary supplements, if not used in a balanced way, may be more harmful than previously thought.

"Elderly people as a group are large consumers of vitamin E supplements, which usually contain only ±-tocopherol, and this often at high doses," says Dr Mangialasche. "Our findings need to be confirmed by other studies, but they open up for the possibility that the balanced presence of different vitamin E forms can have an important neuroprotective effect."


Study Information

Mangialasche F, Kivipelto M, Mecocci P, Rizzuto D, Palmer K, Winblad B, Fratiglioni L.
High plasma levels of vitamin E forms and reduced Alzheimer's disease risk in advanced age.
J Alzheimers Dis
2010 April
Aging Research Center, Karolinska Institutet, Stockholm, Sweden.

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